I would say at least 50 miles before you're hard on it. It really doesn't need a break in, but every time you have the differential out it's good to allow the ring and pinion to find a proper wear pattern again. Every time you take it apart you don't get the exact same wear pattern on it again. You also give a few miles for the bearings to wear in, loosen up, and get a good coating of lube on everything new.

 

the 500 miles is for the ring and pinion to break in. not the carrier. i swapped the gears i was currently running onto the detroit trutrac and was doing 30mph punches within a mile.

if you install a new gear set with the new carrier definately do the 500 mile break in.

 

i did gears first and first drive with them was burnout and run to 6200 rpm at 1-2 shift then let out and said itll hold!!! trutrac came 5-6 months later and done the same thing. the only noise you'll get is if they arent setup in tolerance. install them closer to the tighter side of the tolerance and you'll never have a problem. from the experiences ive had!!!!!!!!!!